贵刊87年第5期《一个力学问题的探讨》一文中的题目有简单的解法。题目:一根密度均匀,截面为圆形,由粗逐渐变细的长棒,如果通过重心沿轴线的垂直方向将它截为二段,问哪段重? 解:如附图示,设将棒在O点支起,棒能平衡在水平位置,显然粗端短,细端长。把左边的木棒分成阴影部分和A两部分,把右边的木棒分成B和C两部分,并且让A跟B左右对称,则它们的重量相等,产生的重力短平衡。再看左边的阴影部分跟右边的C部分。由于阴影部分的重心必落在A内,即重心离O点的距离l_1< There is a simple solution to the problem in the article “Discussion of a Mechanical Problem” in the 5th issue of your magazine, 87th. Title: A long rod with a uniform density, a circular cross section, and a taper from the coarse, if it is cut into two segments in the vertical direction along the axis by the center of gravity, which segment is the solution? The stick is set up at point O. The stick can be balanced in the horizontal position. Obviously, the short end is short and the long end is long. Divide the left stick into two parts, the shadow part and the A part, and divide the right stick into two parts, B and C. Let A and B be symmetric, their weight is equal, and the resulting gravity is short-balanced. Look at the shaded part on the left and the part C on the right. Since the center of gravity of the shaded part must fall within A, that is, the distance from the O point to the center of gravity, l_1<